Fix DD tracker addition. (#2751)

DD uses a wrapped tracker. Check only stream tracker manager field for
existing tracker.

pkg/sfu/streamtrackermanager.go

@@ -170,37 +170,40 @@ func (s *StreamTrackerManager) AddDependencyDescriptorTrackers() {
 func (s *StreamTrackerManager) AddTracker(layer int32) streamtracker.StreamTrackerWorker {
 	var tracker streamtracker.StreamTrackerWorker
 	s.lock.Lock()
-	if s.ddTracker != nil {
-		tracker = s.ddTracker.LayeredTracker(layer)
-	} else {
-		tracker = s.trackers[layer]
-	}
-	s.lock.Unlock()
+	tracker = s.trackers[layer]
 	if tracker != nil {
+		s.lock.Unlock()
 		return tracker
 	}
 
+	if s.ddTracker != nil {
+		tracker = s.ddTracker.LayeredTracker(layer)
+	}
+	s.lock.Unlock()
+
 	bitrateInterval, ok := s.trackerConfig.BitrateReportInterval[layer]
 	if !ok {
 		return nil
 	}
 
-	var trackerImpl streamtracker.StreamTrackerImpl
-	switch s.trackerConfig.StreamTrackerType {
-	case config.StreamTrackerTypePacket:
-		trackerImpl = s.createStreamTrackerPacket(layer)
-	case config.StreamTrackerTypeFrame:
-		trackerImpl = s.createStreamTrackerFrame(layer)
-	}
-	if trackerImpl == nil {
-		return nil
-	}
+	if tracker == nil {
+		var trackerImpl streamtracker.StreamTrackerImpl
+		switch s.trackerConfig.StreamTrackerType {
+		case config.StreamTrackerTypePacket:
+			trackerImpl = s.createStreamTrackerPacket(layer)
+		case config.StreamTrackerTypeFrame:
+			trackerImpl = s.createStreamTrackerFrame(layer)
+		}
+		if trackerImpl == nil {
+			return nil
+		}
 
-	tracker = streamtracker.NewStreamTracker(streamtracker.StreamTrackerParams{
-		StreamTrackerImpl:     trackerImpl,
-		BitrateReportInterval: bitrateInterval,
-		Logger:                s.logger.WithValues("layer", layer),
-	})
+		tracker = streamtracker.NewStreamTracker(streamtracker.StreamTrackerParams{
+			StreamTrackerImpl:     trackerImpl,
+			BitrateReportInterval: bitrateInterval,
+			Logger:                s.logger.WithValues("layer", layer),
+		})
+	}
 
 	s.logger.Debugw("stream tracker add track", "layer", layer)
 	tracker.OnStatusChanged(func(status streamtracker.StreamStatus) {